Its very important to have the model number and the serial number when ordering parts for a Rinnai tankless heater. There parts may look the same but there are slight differences in them and it will just prolong the time it takes to get the hot water back on.
A good tip is to make sure you have a good selection of screws, o rings before you start any repair on any unit.

These repairs should be done by a licensed plumber trained in level three by Rinnai.
When installing, servicing and repairing any Rinnai unit or any part of the plumbing or gas system, make sure you follow all state and local plumbing and gas codes and you file a permit with your local building department.

If you have a question please e mail me at [email protected]
I hope you enjoy this video and I hope it helps you in your future repairs.
Mike